Although electromagnetic radiation can be generated from any number of sources, including natural phenomenon like lightning strikes, the emergence of electronic devices, and specifically telecommunication devices, has rapidly increased the amount of electromagnetic radiation propagating through the air. This electromagnetic radiation can interfere with electronic devices by causing a current to flow through wires and other metallic objects. Since this extraneous current may generate unwanted signals, including a spike in current that can damage electronic components, some treat the rapid increase in electromagnetic radiation as a form of pollution. In addition, electromagnetic energy produced from internal electromagnetic sources, such as high current cables, can also radiate out of the wire and interfere with other electronic devices.
One way to combat these extraneous currents is to protect the wires of electronic devices from external electromagnetic radiation by using a braided metallic shield that covers and extends along the length of the wire. The braided metallic shield also prevents electromagnetic radiation from leaking out of the wire, reducing interference to external devices.
The braided shield generally includes a solid metal support crimped to a terminal end of the shield. Although generally effective, there are several difficulties when crimping the support to the shield. For instance, it may be difficult to spread the shield evenly over the support. Also, it may be difficult to hold the shield in place while trying to crimp the support to the shield, which may cause the shield to bunch on one side or have minimal contact pressure at certain places relative to the support, resulting in inconsistent crimps. In addition, the terminal end of the shield may need to be expanded when inserting the support, which separates the wires that form the braid in the shield, creating “holes.” Unfortunately, the “holes” allow electromagnetic radiation to penetrate through the wire and interfere with transmitted signals on the wire, or allow electromagnetic radiation to escape the wire and interfere with external devices. Further, as the terminal end of the shield ages, the wires that make up the shield may begin to unravel, causing additional “holes” in the shield and weakening the crimp. The unraveling may further result in stray wires that require trimming. Moreover, the terminal end of the shield, as it begins to unravel, can cause galvanic corrosion between the shield and the metal support. Finally, determining the pull strength of the cable may be difficult when crimped in such a way.
Accordingly, an electromagnetically shielded cable is needed that provides a strong and consistent crimp between the shield and the shell.